China coronavirus: Beijing should close down live-animal food markets to stop similar diseases emerging in future

South China Morning Post Dipublikasikan 00.01, 25/01/2020
China coronavirus: Beijing should close down live-animal food markets to stop similar diseases emerging in future

Pandemic diseases have sometimes caused huge death tolls in history - notably, bubonic plague killed an estimated 50 million in Europe alone during the 14th century, and the Spanish flu pandemic of 1918 infected maybe 500 million people worldwide, killing between 20 and 50 million. Thus, the emergence of a new disease is understandably attention-grabbing.

That's the case now, given the sudden outbreak of a coronavirus that is likely to have originated among exotic animals sold for food in mainland China, and which strongly recalls the Sars pandemic that killed 299 of the 1,755 people infected in Hong Kong in 2003.

Perhaps it's all too easy to get caught up in notions of imminent doom, like in a real-life disaster movie. I've been there before, transfixed by dire online predictions about severe acute respiratory syndrome, and influenza researcher Robert Webster's warning that bird flu could kill up to half the human population.

But science reveals that such fears are groundless, while also pointing towards steps that individuals and governments can take to reduce the spread of disease and the potential for pandemics.

While it may not seem obvious, this coronavirus can't become widespread while causing a significantly higher fatality rate: it is capable of mutating and evolving, which can put a natural brake on its virulence.

Although such Darwinian principles seem to have been overlooked by virologists like Webster, they have been successfully applied to disease by evolutionary biologist Paul Ewald, director of the programme in evolutionary medicine at the University of Louisville.

Ewald's insights originated with a bout of diarrhoea, during which he wondered why the symptoms included expelling huge amounts of the pathogenic bacteria. He realised this mechanism could actually help the diarrhoea spread, and began looking at the relationship between evolution and the virulence of diseases.

Influenza - flu - interested Ewald, partly because it can change quickly. While most strains are relatively benign, flu can become more virulent, with a higher fatality rate. Ewald realised that flu strongly relies on human-to-human transmission: infected people have to be well enough to move around for flu to spread, which typically means the disease must be mild.

But what about Spanish flu? Ewald decided the timing of that outbreak did not just coincide with the first world war (1914-1918). Instead, the pandemic was a product of that war, especially trench warfare.

Diagram showing the conditions in a Wuhan street market. Image: SCMP

People struck down by a severe bout of flu are usually bedridden, and unlikely to interact with many people at home or in hospital. However, soldiers with flu during the war would have been in the trenches and field hospitals, near tens or hundreds of other people. It was under these conditions that the virus evolved into a more potent form.

But even as it began spreading, wartime censors played down reports of its severity; the name derives from uncensored news reports in Spain, which was neutral during the war.

Although not all disease experts agree with Ewald, his theories regarding diseases and evolution have been tested and sometimes proved true.

As Esquire magazine once noted: "Paul Ewald is a short-seller of global pandemics. He bets against them when panic reaches its peak - when natural precaution has turned to frenzy, and experts who should know better turn into shameless touts. He has short-sold Sars and bet against bird flu, and in both cases he was famously right."

That article appeared in 2014, when there were concerns about a deadly Ebola pandemic. Ewald forecast then that the highly lethal Ebola virus would be contained, or would have to someday become a mild disease to survive in humans.

With no word from Ewald to me regarding the Wuhan coronavirus, perhaps it's worth guessing what evolutionary biology might tell us. It's early days, and there is relatively little information, but indications are that the new coronavirus is less virulent than Sars.

Professor Neil Ferguson, of Imperial College London, has told Yahoo! News the death rate of 2019-nCoV could be 2 per cent, similar to that of Spanish flu. So, just maybe, this means it can be readily transmitted by mobile people, and might indeed cause a pandemic. Of course, only time will tell.

At the level of individuals, there has been a focus on face masks, like in 2003. Yet it is questionable whether they are really useful, with a review of research into face masks and flu concluding: "There is little evidence to support the effectiveness of face masks to reduce the risk of infection." I even wonder if they just give a false sense of security, especially the paper masks that easily let in small particles.

Other research into viruses including flu has found that while droplets carrying a virus stay airborne for up to 10 minutes after an infected person sneezes, they then stick to surfaces and remain infectious for hours, or even a day or more on hard surfaces.

So the advice on washing hands, and maybe using hand sanitisers, is highly important; also, do resist the temptation to scratch or rub an itchy eye or nose.

The importance of this advice was highlighted back in 2003, when I interviewed Dr Yannie Soo, who courageously worked in a ward with Sars patients. She told me of a medic in the ward who scratched quickly beneath his mask, which evidently led to him becoming infected.

As for governments, various actions are possible. Screening travellers might seem important, yet in researching for this article I found it to be of limited value, which explains how some cases have slipped through the net. Quarantining the entire city of Wuhan, and others now, is an astonishing measure, especially after the coronavirus has travelled as far as the United States.

Looking ahead, China's most vital course of action is to counter the emergence of similar diseases. Reports link the Wuhan coronavirus to a seafood market that also sells exotic animals; there are many other live food markets in China, which could be mixing pots for diseases.

Sars apparently originated in bats, before spreading through civet cats to humans; early research suggests the Wuhan coronavirus is similar, but could have reached humans from snakes.

As long as such markets exist, the likelihood of other new diseases emerging will remain. Surely it's time for China to close down these markets. In one fell swoop, it would be making progress on animal rights and nature conservation, while reducing the risk of a "made in China" disease harming people worldwide.

Martin Williams is a Hong Kong-based writer specialising in conservation and the environment, with a PhD in physical chemistry from Cambridge University

Copyright (c) 2020. South China Morning Post Publishers Ltd. All rights reserved.

Artikel Asli